The present invention relates to a method and apparatus for cutting fiberglass filament into staple fiber, and in particular to the conversion of bundles of discarded continuous fiberglass filament into usable staple fibers by compressing the fiberglass bundle and conveying the compressed bundle along a pathway into engagement with a rotating cutting blade to cut the continuous filaments into a plurality of staple fibers.
Continuous fiberglass filaments are manufactured by extruding molten glass through a spinneret, followed by attenuating the extruded material. The resultant filaments, after solidifying, may then be directed to another area for conversion into desired products, or collected on a bobbin for storage prior to further processing. Formation of the filaments also normally involves the treatment of the filaments with a binder to enhance the properties of the fiberglass in subsequent operations.
As used in describing the invention, the term "continuous filament" is intended to include a single filament or a plurality of filaments in a strand. Also, a "plurality of filaments" is intended to encompass a plurality of segments of a single filament in adjacent relationships, such as occurs when a single filament is wrapped around a bobbin tube.
When fiberglass packages are formed, the continuous filament is wound onto a tube utilizing various methods and apparatus well known in the pertinent art. When the package is to be used in a subsequent process, the tube is removed from the interior of the package. The inner end of the filament is then pulled from within the interior of the package to unwind the filament.
Waste fiberglass filament is produced during both extrusion of the fiberglass and during its subsequent use. For example, at the beginning of the extrusion process, the practice is to draw the initial filaments from the spinneret until uniform filaments are obtained, and then begin winding of the filaments. These initial filament segments are then discarded, or reclaimed by melting.
In use, all of the filament may not be unwound from the package as a result of the adhesion of adjacent filament sections on the outer part of the package. The final portion of the package comprised of a continuous band of fiberglass filament adhered by the treatment material, and commonly referred to in the pertinent industry as a "hull," has normally been discarded.
Other steps in the production of fiberglass, or in its subsequent use, can produce reject segments of fiberglass filaments or a combination of filament and clumps of pieces of fiberglass produced by discharge of molten fiberglass. These materials, and the above hulls, collectively referred to herein as "fiberglass filament waste," may be discarded, which is undesirable from both an economic as well as an environmental standpoint. In some instances, the material may be remelted and extruded again. However, conversion of the filament waste into a useful staple fibers having utility in various known applications, such as in the reinforcement of molded plastic articles or insulation, is preferred.
Numerous prior art patents describe cutting of fiberglass filaments into staple fiber. Generally, the apparatus and method disclosed in these patents involves engaging a continuous strand of one or a few fiberglass filaments immediately after extrusion, with a chopping roller rotating perpendicular to the path of the strand. The chopping roller is comprised of a roller core with a plurality of spaced chopping blades projecting radially outwardly from, and parallel to, the axis of the core. Normally, filaments are engaged between the blades of the chopping roller and an adjacent surface to create a bending action, breaking the continuous filaments into staple fiber segments.
Examples of these prior art teachings include the following patents:
______________________________________ U.S. Pat. No. Inventor(s) ______________________________________ 5,003,855 Ciupak 4,706,531 Blauhut et al. 4,637,286 Boggs 4,576,621 Chappelear et al. 4,373,650 Gay 4,287,799 Fujita et al. 4,265,151 Carruth et al. 4,254,536 Lehner 4,237,758 Lindner et al. 4,043,779 Schaefer 3,873,290 Marzocchi 3,815,461 Genson 3,648,554 Arnold et al. 3,508,461 R. M. Stream ______________________________________
While the apparatus and methodology described in the above patents is suitable for chopping continuous, extruded fiberglass filament into staple fibers, conversion of bundles of fiberglass filaments comprised of a substantial number of filaments, such as fiberglass hulls or other bundles of waste, into useful staple fiber is not possible in the described manner, since the waste simply contains too many filaments to be broken into staple lengths by the action of chopper blades. Instead, a method and apparatus operating on an entirely different principal is necessary.
Commonly assigned U.S. Pat. No. 5,678,774, issued Oct. 21, 1997; and U.S. Pat. No. 5,697,560, issued Dec. 16, 1997; both being incorporated herein by reference, describe methods and apparatus suitable for cutting bundles of fiberglass filaments into fiberglass staple. As described in these patents, a hull or other fiberglass bundle is conveyed under compression into the nip of a pair of rollers, namely a cutting roller and a compression roller. The cutting roller is comprised of a plurality of spaces rotating cutting blades having a spacing approximating the length of the desired fiberglass staple.
The compression roller includes a plurality of circumferential grooves to receive the cutting blades. The filaments of the fiberglass bundle are oriented substantially transverse to the axis of the conveyor. As the filaments enter the nip of the roller pair, they are cut into staple lengths. U.S. Pat. No. 5,697,560 further includes a second roller pair to chop staple exiting from the first roller pair, to increase the uniformity of the staple.
The above methods and apparatus have been found to perform well in the cutting of fiberglass hulls and other materials comprised of a plurality of filaments of a relatively limited volume, with the bundles being of generally uniform size. However, some fiberglass waste is of a relatively greater size. Also, the size of the bundles being cut may vary considerably. These fiberglass bundles also may be comprised of a mixture of filament and fiberglass drippings, requiring a different form of cutting. Also, a cutter operating at a considerably higher speed is needed. In order to facilitate the cutting of these materials, it has been found that certain modifications to the methods and apparatus described in the above patents is needed.
Accordingly, it is an aspect of the present invention to provide an improved method and apparatus for cutting bundles of fiberglass filament waste. It is a particular objective of the present invention to provide a method and apparatus for compressing and cutting bundles of continuous fiberglass filament into staple fiber using a single roller comprised of a plurality of rotating cutting blades positioned at the exit of, and substantially transverse to the axis of a bundle conveyor that is adapted to compress fiberglass bundles of varying size.